32 patients with scaphoid non-union were examined to clarify the relationship between pre-operative radiographic sclerosis in the proximal fragment and signal intensity on magnetic resonance imaging (MRI). In addition, the correlation between changes in signal intensity in the proximal fragment and surgical outcome after bone grafting and internal fixation was investigated. Proximal fragment sclerosis was observed in seven patients. Comparison of the T1 and T2-weighted images with those of the 25 patients without proximal fragment sclerosis revealed no differences. Therefore, there was no relationship between sclerotic changes on plain radiography and the degree of avascularity of the proximal fragment assessed by MRI. None of the patients who had low signal intensity on both T1 and T2-weighted images achieved union within 5 months after surgery. Thus the detection of signal intensity on both T1 and T2-weighted images can be useful to predict the prognosis after the surgery.